For decades, Debbie Baker was resigned to living her life at 300 lbs. She had gained weight in college — she would down an entire pizza by herself late at night — and then added more after giving birth to her two daughters. As a kindergarten teacher, she spent her days with kids who left her too exhausted to move when she got home.

“I would just take out a sleeve of saltine crackers and put butter on them, and I would eat that whole sleeve because I was tired and exhausted, and then I would wonder why my weight wouldn’t go anywhere,” Baker, 57, tells PEOPLE for the 2019 Half Their Size issue.

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She had tried every diet imaginable, but any success only lasted a few weeks, and then her weight would go right back up. The years of yo-yo dieting left Baker with “very low self-esteem.”

“I was always very negative about myself,” she says. “You walk into a place and you can feel the eyes. I knew what they were thinking: ‘What’s wrong with her, she needs to lose weight.’ “

Debbie Baker in 2014

Debbie Baker

And she was also accustomed to the 5-year-olds at school telling people, “My teacher is the fat one.”

“The only person that never said anything was my husband,” she adds. “He just was always there for whatever decision I made — he was right behind me.”

Baker and her family lived in Ohio for years, but she had to move to Florida for an autoimmune disorder unrelated to her weight. Suddenly they were in a town where they didn’t know anyone, and it was there that she saw an ad for TOPS, or Take Off Pounds Sensibly, a weight loss support group. That gave her the idea to give it a shot.

“I was like, ‘Well I don’t know anybody, so why not?’ “ she says. But the final straw came after she decided to throw her fast food leftovers in the yard for the birds — and a week later, they were still there.

“The birds wouldn’t touch them,” she says. “I decided that if the birds aren’t eating them, then I shouldn’t either. And that’s when it all clicked. This is not healthy.”

For more stories of women who lost half their size, pick up a copy of PEOPLE, on newsstands now.

Baker signed up for TOPS soon after, and immediately felt comfortable. The program is just a support group — members are expected to lose weight on their own through the diet plan of their choice — and she loved the community. Baker decided to cut her calories down to 1,500 a day, and started tracking her meals with MyFitnessPal. She also got a Fitbit and started by walking from her driveway to her neighbor’s, and she would add another driveway to her route each day.

“At first I was hungry a lot,” she says. “My stomach would rumble and it was really hard, but I was determined.” And from past dieting experience, Baker knew that her eating habits had to be sustainable or she would give up, so she decided to give herself one day each week where she could eat what she wanted. “That way I don’t feel deprived, and I don’t binge.”

“I walked in there and nobody said anything about my weight. They just all were very welcoming and warm, and then the next week I had lost four pounds and they’re all standing up and cheering,” she says. “I’ve been in it since 2014 and still, anytime anybody loses a quarter of a pound, we all stand up and cheer for them. That makes a difference to people to know that you’re not out there alone.”

Baker hit her goal weight — 159 lbs. down — in July 2017, and is now the leader of her TOPS group. These days she’s doing things she never thought would be possible, like riding a bike, and is even preparing for a 30-mile bike ride in her area.